Artificial Intelligence and Expert Systems Leroy Garcia 1
Feb 23, 2016
Artificial Intelligence and Expert Systems
Leroy Garcia
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Definition of AI
Artificial Intelligence is the branch of computer science that is concerned with the automation of intelligent behavior (Luger, 2008).
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Different Approaches to AI
Systems that think like humans
Systems that think rational
Systems that act like humans Systems that act rational
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History
Aristotle Rene Descartes Frances Bacon John Locke David Hume Ludwig Wittgenstein Bertrand Russell Rudolf Carnap Carl Hempel Alan Turing
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Alan Turing
Wrote “Computer Machinery and Intelligence”.
The Turing Test
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Dartmouth 1956
Automatic ComputersHow can computers be programmed
to use a language?Neuron NetsTheory of the Size of a CalculationSelf-Improvement (Machine
Learning)AbstractionsRandomness and Creativity
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Acting Human
Natural Language ProcessingKnowledge RepresentationAutomated ReasoningMachine Learning
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Rational Agents
Anything that can be viewed as perceiving it’s environment through sensors and acting upon it’s environment through actuators.
(Russell & Norvig, 2003)
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Rational Agents cont.
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PEAS
Performance Measure EnvironmentActuatorsSensors
Task Environment Made up of PEAS.
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Examples of Agent Types and PEAS
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Dimensions of a Task EnvironmentFully Observable vs. Partially
ObservableDeterministic vs. StochasticEpisodic vs. SequentialStatic vs. DynamicDiscrete vs. ContinuousSingle Agent vs. Multiagent
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Fully Observable vs. Partially Observable
Fully Observable Sensors must provide a complete state
of environment.
Partially Observable Usually due to poor an inaccurate
sensors or if parts of the world are missing the sensor’s data.
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Deterministic vs. StochasticDeterministic
The action of the next state depends on the action of the previous state.
Stochastic Actions do not depend on previous state.
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Episodic vs. Sequential
Episodic Single actions are performed.
Sequential Future decisions are determined by the
current action.
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Static vs. Dynamic
Static Does not change during an agent’s
deliberation.
Dynamic Able to change during an agent’s
deliberation.
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Discrete vs. Continuous
Discrete Contains finite number of distinct states
and a discrete state of percepts and actions.
Continuous Contains a range of continuous values
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Single Agent vs. MultiagentSingle Agent
One agent is needed to execute an action on a given environment.
Multiagent More than one agent is needed to
execute an action on a given environment.
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Examples of Agents and Task Environments
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Types of Agents
Simple Reflex AgentModel Based Reflex AgentGoal Based AgentUtility AgentLearning AgentProblem Solving Agent
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Simple Reflex Agent
Selects action based on the current percept and pays no attention to any previous percept.
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Model Based Reflex Agent Maintains at least some form of internal state
that depends on the percept history and thereby reflects some of the unobserved aspects of the current state.
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Goal Based Agent
Performs actions based on a specific goal.
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Utility Based Agent
Takes into account it’s current environment and decides to act on an action that simply makes it happier.
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Learning Agent
Learning ElementPerformance ElementCriticProblem Generator
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Learning Agent cont.
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Problem Solving Agent
State Space Initial StateSuccessor FunctionGoal TestPath Cost
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Example of States
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Searching for Solutions
Search Tree States Parent Node Action Path Cost Depth
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Evaluation of a Search
CompletenessOptimalityTime ComplexitySpace Complexity
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Various Types of SearchesBreadth-First SearchUniform-Cost SearchDepth-First SearchDepth-Limited Search Iterative Deepening Depth-First
Search
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Breadth-First Search
Expands the root node first, then all the root node successors are expanded followed by other successors.
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Uniform-Cost Search
Expands a node with the lowest path cost.
Only cares about the total cost and does not care about the number of steps a path has.
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Depth-First Search Expands the deepest node and the current fringe
of the search tree. Implements a last-in-first-out methodology.
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Depth-Limited Search
Solves infinite path problems and can be implemented as a single modification to the general tree search algorithm by setting a depth limit.
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Iterative Deepening Depth-First Search
Is used to find the best Depth Limit.A goal is found when a Depth Limit
reaches the depth of the shallowest node.
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Iterative Deepening Depth-First Search cont.
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Questions?
Any Questions on AI?
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Expert Systems
Definition “An expert system is an interactive
computer-based decision tool that uses both facts and heuristics to solve difficult decision problems based on the knowledge acquired from an expert.”(The Fundamentals of Expert Systems)
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Types of Expert Systems
Interpreting and IdentifyingPredictingDiagnosingDesigningPlanningMonitoringDebugging and Testing Instructing and TrainingControlling
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Creating an Expert System
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Expert System Programming Languages
PROLOGLISP
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Mandatory Characteristics
Efficient mix of integer and real variables Good memory-management procedures Extensive data-manipulation routines Incremental compilation Tagged memory architecture Optimization of the systems
environment Efficient search procedures
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Levels of an Expert System Knowledge base
Problem-solving rules, procedures, and intrinsic data relevant to the problem domain.
Working memory Task-specific data for the problem under
consideration. Inference engine
Generic control mechanism that applies the axiomatic knowledge in the knowledge base to the task-specific data to arrive at some solution or conclusion.
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Expert Systems Organizational and Operating Environment
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Data Flow of an Expert System
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References Expert Systems: Wikipedia. (n.d.). Retrieved October 18, 2008, from
Wikipedia: wikipedia - http://en.wikipedia.org/wiki/Expert_system Fogel, D. B. (2002). Blondie24: Playing at the Edge of AI. San
Fransisco,CA: Morgan Kaufman Publishers. Luger, G. F. (2008). Artificial Intelligence. Boston: Pearson Addison
Wesley. Russell, S., & Norvig, P. (2003). Artificial Intelligence: A Modern
Approach. Upper Saddle River, NJ: Pearson Education Inc.
The Fundamentals of Expert Systems. (n.d.). Retrieved November 13, 2008, from http://media.wiley.com/product_data/excerpt/18/04712933/0471293318.pdf
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The End
Any Questions?
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